Conventionally, a through-hole is provided in a vehicle body panel such as a dash panel that partitions an engine room from a vehicle cabin in an automobile, and commonly, a wire harness is arranged to span between an engine room and a vehicle cabin through the through-hole. When a wire harness is thus arranged, a grommet is provided between the wire harness and the through-hole in the vehicle body panel to prevent water, dust, or noise from entering from a gap in the through-hole.
A flange is provided in many through-holes in vehicle body panels. For a vehicle body panel that includes a flange, the shape of a grommet needs to be designed while giving consideration to the shape of the flange to ensure waterproofability.
Patent Document 1 (JPH4-249817A) describes an example of a grommet that is to be fitted to a through-hole with a flange provided in a vehicle body panel. A grommet 9 described in Patent Document 1 includes a tapered portion 2 and a fitting portion 3 as shown in FIG. 7A, and the fitting portion 3 includes a first groove portion 4, a second groove portion 6, a ring-shaped protrusion 5, and a collar portion 7. The flange in the panel 8 stands upright.
If this grommet 9 is fitted to the panel 8, the standing portion of the flange presses the ring-shaped protrusion 5 and ensures waterproofability by sealing the grommet 9 at three points, namely points X,Y, and Z in FIG. 7B.